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nfsd4: Move callback setup to callback queue 

Instead of creating the new rpc client from a regular server thread,
set a flag, kick off a null call, and allow the null call to do the work
of setting up the client on the callback workqueue.

Use a spinlock to ensure the callback work gets a consistent view of the
callback parameters.

This allows, for example, changing the callback from contexts where
sleeping is not allowed.  I hope it will also keep the locking simple as
we add more session and trunking features, by serializing most of the
callback-specific work.

This also closes a small race where the the new cb_ident could be used
with an old connection (or vice-versa).

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
J. Bruce Fields 2010-06-04 20:04:45 -04:00 committed by J. Bruce Fields
parent fb00392326
commit 6ff8da0887
3 changed files with 63 additions and 27 deletions
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73
fs/nfsd/nfs4callback.c
View File

@ -284,7 +284,7 @@ nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
struct xdr_stream xdr;
struct nfs4_delegation *args = cb->cb_op;
struct nfs4_cb_compound_hdr hdr = {
.ident = args->dl_ident,
.ident = cb->cb_clp->cl_cb_ident,
.minorversion = cb->cb_minorversion,
};
@ -506,7 +506,8 @@ int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
PTR_ERR(client));
return PTR_ERR(client);
}
nfsd4_set_callback_client(clp, client);
clp->cl_cb_ident = conn->cb_ident;
clp->cl_cb_client = client;
return 0;
}
@ -569,15 +570,12 @@ void do_probe_callback(struct nfs4_client *clp)
*/
void nfsd4_probe_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
{
int status;
BUG_ON(atomic_read(&clp->cl_cb_set));
status = setup_callback_client(clp, conn);
if (status) {
warn_no_callback_path(clp, status);
return;
}
spin_lock(&clp->cl_lock);
memcpy(&clp->cl_cb_conn, conn, sizeof(struct nfs4_cb_conn));
set_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_cb_flags);
spin_unlock(&clp->cl_lock);
do_probe_callback(clp);
}
@ -730,19 +728,16 @@ void nfsd4_destroy_callback_queue(void)
}
/* must be called under the state lock */
void nfsd4_set_callback_client(struct nfs4_client *clp, struct rpc_clnt *new)
void nfsd4_shutdown_callback(struct nfs4_client *clp)
{
struct rpc_clnt *old = clp->cl_cb_client;
clp->cl_cb_client = new;
set_bit(NFSD4_CLIENT_KILL, &clp->cl_cb_flags);
/*
* After this, any work that saw the old value of cl_cb_client will
* be gone:
* Note this won't actually result in a null callback;
* instead, nfsd4_do_callback_rpc() will detect the killed
* client, destroy the rpc client, and stop:
*/
do_probe_callback(clp);
flush_workqueue(callback_wq);
/* So we can safely shut it down: */
if (old)
rpc_shutdown_client(old);
}
void nfsd4_release_cb(struct nfsd4_callback *cb)
@ -751,15 +746,51 @@ void nfsd4_release_cb(struct nfsd4_callback *cb)
cb->cb_ops->rpc_release(cb);
}
void nfsd4_process_cb_update(struct nfsd4_callback *cb)
{
struct nfs4_cb_conn conn;
struct nfs4_client *clp = cb->cb_clp;
int err;
/*
* This is either an update, or the client dying; in either case,
* kill the old client:
*/
if (clp->cl_cb_client) {
rpc_shutdown_client(clp->cl_cb_client);
clp->cl_cb_client = NULL;
}
if (test_bit(NFSD4_CLIENT_KILL, &clp->cl_cb_flags))
return;
spin_lock(&clp->cl_lock);
/*
* Only serialized callback code is allowed to clear these
* flags; main nfsd code can only set them:
*/
BUG_ON(!clp->cl_cb_flags);
clear_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_cb_flags);
memcpy(&conn, &cb->cb_clp->cl_cb_conn, sizeof(struct nfs4_cb_conn));
spin_unlock(&clp->cl_lock);
err = setup_callback_client(clp, &conn);
if (err)
warn_no_callback_path(clp, err);
}
void nfsd4_do_callback_rpc(struct work_struct *w)
{
struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work);
struct nfs4_client *clp = cb->cb_clp;
struct rpc_clnt *clnt = clp->cl_cb_client;
struct rpc_clnt *clnt;
if (clnt == NULL) {
if (clp->cl_cb_flags)
nfsd4_process_cb_update(cb);
clnt = clp->cl_cb_client;
if (!clnt) {
/* Callback channel broken, or client killed; give up: */
nfsd4_release_cb(cb);
return; /* Client is shutting down; give up. */
return;
}
rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
cb->cb_ops, cb);

7
fs/nfsd/nfs4state.c
View File

@ -207,7 +207,6 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
{
struct nfs4_delegation *dp;
struct nfs4_file *fp = stp->st_file;
struct nfs4_cb_conn *conn = &stp->st_stateowner->so_client->cl_cb_conn;
dprintk("NFSD alloc_init_deleg\n");
/*
@ -234,7 +233,6 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
nfs4_file_get_access(fp, O_RDONLY);
dp->dl_flock = NULL;
dp->dl_type = type;
dp->dl_ident = conn->cb_ident;
dp->dl_stateid.si_boot = boot_time;
dp->dl_stateid.si_stateownerid = current_delegid++;
dp->dl_stateid.si_fileid = 0;
@ -875,7 +873,7 @@ expire_client(struct nfs4_client *clp)
sop = list_entry(clp->cl_openowners.next, struct nfs4_stateowner, so_perclient);
release_openowner(sop);
}
nfsd4_set_callback_client(clp, NULL);
nfsd4_shutdown_callback(clp);
if (clp->cl_cb_conn.cb_xprt)
svc_xprt_put(clp->cl_cb_conn.cb_xprt);
list_del(&clp->cl_idhash);
@ -978,6 +976,7 @@ static struct nfs4_client *create_client(struct xdr_netobj name, char *recdir,
INIT_LIST_HEAD(&clp->cl_delegations);
INIT_LIST_HEAD(&clp->cl_sessions);
INIT_LIST_HEAD(&clp->cl_lru);
spin_lock_init(&clp->cl_lock);
INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_do_callback_rpc);
clp->cl_time = get_seconds();
clear_bit(0, &clp->cl_cb_slot_busy);
@ -1547,7 +1546,7 @@ nfsd4_destroy_session(struct svc_rqst *r,
nfs4_lock_state();
/* wait for callbacks */
nfsd4_set_callback_client(ses->se_client, NULL);
nfsd4_shutdown_callback(ses->se_client);
nfs4_unlock_state();
nfsd4_put_session(ses);
status = nfs_ok;

10
fs/nfsd/state.h
View File

@ -84,7 +84,6 @@ struct nfs4_delegation {
u32 dl_type;
time_t dl_time;
/* For recall: */
u32 dl_ident;
stateid_t dl_stateid;
struct knfsd_fh dl_fh;
int dl_retries;
@ -217,10 +216,17 @@ struct nfs4_client {
/* for v4.0 and v4.1 callbacks: */
struct nfs4_cb_conn cl_cb_conn;
#define NFSD4_CLIENT_CB_UPDATE 1
#define NFSD4_CLIENT_KILL 2
unsigned long cl_cb_flags;
struct rpc_clnt *cl_cb_client;
u32 cl_cb_ident;
atomic_t cl_cb_set;
struct nfsd4_callback cl_cb_null;
/* for all client information that callback code might need: */
spinlock_t cl_lock;
/* for nfs41 */
struct list_head cl_sessions;
struct nfsd4_clid_slot cl_cs_slot; /* create_session slot */
@ -439,7 +445,7 @@ extern void nfsd4_do_callback_rpc(struct work_struct *);
extern void nfsd4_cb_recall(struct nfs4_delegation *dp);
extern int nfsd4_create_callback_queue(void);
extern void nfsd4_destroy_callback_queue(void);
extern void nfsd4_set_callback_client(struct nfs4_client *, struct rpc_clnt *);
extern void nfsd4_shutdown_callback(struct nfs4_client *);
extern void nfs4_put_delegation(struct nfs4_delegation *dp);
extern __be32 nfs4_make_rec_clidname(char *clidname, struct xdr_netobj *clname);
extern void nfsd4_init_recdir(char *recdir_name);